Conventional building structures are typically square, rectangular, and circular in horizontal section, and although some of them use walls having a variety of curves as outer walls and the like, structures which horizontal section is elliptical are not often encountered. If structures which outer walls partly adopts an elliptic curve can be encountered, those which are entirely elliptical in horizontal section, in other words, which entire perimeter forms an elliptical cylinder are rarely encountered. However, structures which horizontal section is elliptical are extremely graceful in shape, and have a high strength, therefore, as future building structures providing a novel feeling and a beautiful appearance, they can be greatly expected to be popularized.
Then, the present invention provides efficient and economic means for serving the design, drawing, land survey, manufacture, and construction in building an elliptical structure.
The elliptic curve is a quadratic curve which is characterized in that the sum of the distances from a particular point thereon to the two focuses of ellipse is constant. For drawing an elliptic curve, two coordinate points which are to be on the elliptic curve may be connected to each other with a single straight line as a convenient method, or with a polygonal line approximate to the elliptic curve as a more precise method. However, for connecting two coordinate points to each other with a polygonal line, the distance between the two coordinate points must be finely divided, and minute polygonal line components must be drawn, being connected to one another. Therefore, to connect two coordinate points by means of such a polygonal line to provide an approximate elliptic curve, complex computations and operations are required. Thus, using such an approximate elliptic curve which is thus obtained means that it requires intricate calculations and drawings in designing an elliptical structure, and that it is not efficient, economical, and feasible in land surveying on the building site for the elliptical structure, and fabricating member materials for the structure.